This application claims priority of Korea patent Application No. 10-2000-0069435, filed on Nov. 22, 2000.
(a) Field of the Invention
The present invention relates to an acoustic mirror holographic system, and more particularly to a real-time noise source visualizing system using an acoustic mirror, in which sounds generated during a wind tunnel test may be measured and positions of where the sounds are generated may be visually perceived.
(b) Description of the Related Art
Vehicles often undergo wind tunnel tests to measure air resistance, lift, and the degree of shaking and noise generation caused by the flow of crossing winds. In such wind tunnel tests, the vehicle is placed on a balance system in a closed area, and large amounts of air are forced into the area so that the various measurements can be taken.
However, in the wind tunnel as described above, walls provided to enclose the vehicle influence the air stream, which is generated by the wind following the outer surface of the vehicle, thereby causing a blockage effect. Accordingly, the degree of air resistance, vehicle shaking caused by the air resistance, and areas at which sound is generated cannot be precisely measured.
Therefore, in order to precisely measure the positions where sound is generated as a result of air resistance, an acoustic mirror holographic system as shown in FIG. 1 is used. The acoustic mirror holographic system includes a sound source 10 generating sounds occurring as a result of air resistance, an acoustic mirror 11 concavely formed to reflect and converge the sounds generated by the sound source 10, a microphone 12 receiving the sounds reflected and converged by the acoustic mirror 11, and a recording unit (not shown) for recording electronic sound signals received from the microphone 12.
As-described above, the sound waves emitted from the sound source 10 are reflected and converged by the acoustic mirror 11. Accordingly, sound intensity converged by the acoustic mirror 11 is increased at the microphone 12 relative to a free field, with the microphone 12 being provided at a focal point of the converged sound. Therefore, the emission of sound of another area on a surface perpendicular to the acoustic mirror 11 can also be easily measured if the acoustic mirror 11 and the microphone 12 are moved by a traverse 13.
As opposed to a typical one-dimensional microphone 12 array, it is possible to determine the positions of sounds of all directions perpendicular to the axis of the acoustic mirror 11. However, with the above acoustic mirror holographic system, to determine the position of sounds of specific frequencies, a microphone is attached to the acoustic mirror, and pertinent data is recorded as the microphone and acoustic mirror are positioned by the traverse. Next, this recorded information is stored, and then a holographic process is performed using an instrument that analyzes the stored information. All these processes must be performed to find sounds of specific frequencies.
Therefore, much hardware is needed, and the time required for data analysis is substantial such that real-time measurements are not possible.
The present invention has been made in an effort to solve the above problems.
It is an object of the present invention to provide a real-time noise source visualizing system using an acoustic mirror, in which sounds generated during a wind tunnel test may be measured and positions of where the sounds are generated may be visually perceived such that methods to correct the factors leading to the generation of sounds may be quickly devised.
To achieve the above object, the present invention provides a noise source visualizing system used in a wind tunnel test to measure generated sounds, the system comprising an acoustic mirror for converging sound waves of sounds generated on a surface of a vehicle during a wind tunnel test; a microphone mounted at a position where the sound waves are converged by the acoustic mirror, the microphone measuring the converged sound waves; an image-photographing unit mounted to one side of the microphone and which photographs locations on the vehicle at which the sounds are generated; a first display unit mounted to a distal end of the image-photographing unit, and which performs display of the sounds measured by the microphone as colors that vary according to characteristics of the sounds; a traverse to which the acoustic mirror is connected and which is mounted near a side of the vehicle, and which is able to move up and down and along a length of the vehicle to positions for enabling the acoustic mirror to collect the sounds; a workstation for analyzing the converged sound waves measured by the microphone, the images photographed by the image-photographing unit, and the signals displayed through the first display unit; and a second display unit overlapping then displaying image signals photographed by the image-photographing unit and the colors displayed on the first display unit.
According to a feature of the present invention, the system further comprises a voltage amplifier for amplifying a voltage measured by the microphone to enable the voltage to be separated into colors at the first display unit.
According to another feature of the present invention, the first display unit the colors on a screen of the first display unit vary according to a voltage measured and amplified in real-time, whereby if the voltage is low, the first display unit displays a bluish tint, and if the voltage is high, the first display unit 60 displays a reddish tint such that if a blue color is displayed, the sound level is interpreted to be low, and if a red color is displayed, it is determined that the sound level is high.